Energy Flows In Buildings Research Articles

Developing energy based benchmark model and detailed energy analysis through school statistical data and field surveys

Approximately 20% of all school facilities, i.e., 7,980 buildings, are at least 40 years old in Korea. As the number of aged buildings is expected to rapidly increase, it is necessary to improve such facilities to protect safe learning environments and save energy. This study aims to develop the energy based benchmark model (EBBM) and utilization for energy saving in school. EBBM can be operated for school buildings, a category encompassing complex buildings with different systems and large gaps between them. To utilization of EBBM allows us to obtain knowledge from the school facility, in order to define and tune data driven analysis rules. Data driven energy analysis also allows ascertaining their expected energy consumption and estimating the possible saving systems by using the building energy flow chart. In this research, Korea education data-base was analyzed to classify energy based benchmark model. Applicability review is conducted through detailed system analysis of 10 schools. The difference between the benchmark model calculated value and the actual value was confirmed to be within 10%. Through the benchmarking model, it is possible to compare energy consumption for buildings of different sizes. Energy consumption by energy source and room type was analyzed through an in-depth status survey. Most of School Classrooms consume the largest amount of energy, with cooling and heating energy constituting the largest proportion.

A Review – Home Renewable Energy Management Systems in Smart Grids

This paper presents a review on the Home Energy Management Systems (HEMS) for renewable energy production and used optimization methods. The HEMS is an important Smart Grid application. It is used to monitor and optimally manage the energy flows in buildings including renewable energy production, energy storage and smart home appliances. In this paper, two different methods for the optimal HEMS are selected and compared: Model Predictive Control (MPC) and Reinforcement Learning (RL). As a conclusion, the RL method can overcome the disadvantages of the MCP in the highly dynamic environment of buildings and renewable energies, and is a promising method for HEMS in Smart Grids. Finally, an experimental set-up of the hybrid renewable energy system is presented and its operation is discussed under the Time-of-Use energy management strategy.

Feasibility Study on Energy Audit and Data Driven Analysis Procedure for Building Energy Efficiency: Bench-Marking in Korean Hospital Buildings

Growths in population, increasing demand for health care services and comfort levels, together with patients on the rise in time spent inside hospitals, assure the upward trend that energy demand will continue in the future. Since the hospital buildings operate 24 hours, 365 days a year for the treatment and restoration of patients, they are approximately 2–3 times more energy-intensive than normal buildings. For this reason, energy efficiency in hospitals is one of the prime objectives for energy policy at regional, national and international levels. This study aims to find how meaningful energy performance, reflecting good energy management and energy conservation measures (ECMs), can be operated for hospital buildings, a category encompassing complex buildings with different systems and large gaps between them. Energy audit allows us to obtain knowledge from the healthcare facility, in order to define and tune data driven analysis rules. The use of benchmarking in the energy audit of healthcare facilities enables immediate comparison between hospitals. Data driven energy analysis also allows ascertaining their expected energy consumption and estimating the possible savings margin by using the building energy flow chart. In the 2015–2017 periods, bench-marking of four public hospitals in Seoul were audited for the energy consumption related to weather conditions, total area, bed numbers, employee numbers, and analyzed for building energy flow by zones, energy sources, systems and equipment. This is a practice-based learning in a hospital project. The results reveal that the average annual energy consumption of a hospital under normal conditions, and energy efficiency factors are divided into energy baselines, energy consumption goals for energy saving and energy usage trends for setting ECMs, respectively. The indicator dependent on the area of inpatients (number of beds) proved to be the most suitable as a reference to quantify the energy consumption of a hospital.

A biophysical approach to the performance diagnosis of human–building energy interaction: Information (bits) modeling, algorithm, and indicators of energy flow complexity

This article addresses the utmost upstream impacts of human–building energy interaction by proposing a network-based model, algorithms, and indicators. Hypothesizing that human behavior is a key factor for the symbiotic development of building and the geobiosphere system, the author seeks emergy (spelled with an “m”)-information integrated measures to indicate dynamic system-level performance of the interaction with building energy flow topology. To validate the hypothesis and methods, four representative building cases were tested on the building form (envelope) of (i) a building with no occupant intervention (baseline), (ii) a building controlled by responsive human behavior (bioclimatic adaptation), (iii) a building with reinforced insulation and behavior-dominated control (passive design), and (iv) a net-zero energy building (NZEB). The results demonstrate that adaptive human behavior in building operation increases the information content and complexity of energy-flow networking, improving performance and sustainability. Findings also reveal that increasing information, complexity, and power (energy availability over time) parallel the general energetic features of developing biophysical systems (greater feedback, internalization, and recycling of materials and energies). It becames clear that active behavioral response is a dominant agent of sustainable environments even on a far broader system scale.

An ecological understanding of net-zero energy building: Evaluation of sustainability based on emergy theory

This study evaluates the sustainability of net-zero energy building (NZEB), in terms of ecosystems development on a global environmental scale, with ecological indices and metrics. Employing Howard Odum's ecosystems theory and emergy (spelled with an “m”), authors attempt to associate building energy consumption with thermodynamic networking of energy quality transformation. All upstream impacts of energy use are evaluated with emergy-based sustainability indicators. A LEED-platinum credited NZEB was chosen for tests and a previous study was revisited to set a baseline (non-NZEB) with refined data for comparative analyses. Findings show that NZEB uses greater nonrenewable emergy to seek a zero-energy budget despite its greater emergy sustainability index (ESI). It was identified that production of renewable energy and the intensification of a climate-modifying function (insulation) required an increase of environmental inputs (construction materials, economic services and labor) with upgraded energy quality. Empower distributions through building components characterize spatial hierarchies of building energy flow. This work demonstrates that building sustainability tends to depend on increasing power, not efficiency, which justifies maximum empower principle in environmental building research.

Electrical energy consumption and utilization time analysis of hospital departments and large scale medical equipment

Predicting the loads of electrical devices is an important part of modeling the energy flows in buildings. In non-residential buildings these loads can have a significant impact on heating and cooling requirements. In the case of hospitals this holds true particularly for areas directly connected to diagnostics and medical treatment. Even though the amount of information concerning these loads has increased in recent years, detailed information based on measured data remains scarce. Thus, within this paper over 20,000h of measured data for operating theaters, intensive care units, examination and treatment rooms as well as large scale medical equipment are analyzed and evaluated. The used methodology allows for the determination of area-specific operating hours and a prediction of time-dependent electrical loads in different hospital departments. It was found that a differentiation of weekdays and weekend days is not appropriate for intensive care units, while the examined operating suites show surprisingly strong similarities with regular “office hours” within the assessed hospital. The presented values extend findings from other recent studies in this field and give a more detailed separation of individual contributions from lighting and different classes of medical equipment.

Exergy analysis of building thermal load and related energy flows in buildings

In this study, the exergy analysis method was extended to analyse the building thermal load and related energy flows, aiming to investigate the exergy loss as well as improvement potential for building design and analysis. Five office buildings in five major climate zones in China were taken as case studies for the analysis. The building thermal loads and related energy flows were calculated and analysed using the exergy analysis method. Results show that the building exergy load is relatively low compared to the building thermal energy load. However, it is always met by consuming energy of high exergy value (e.g. electricity), indicating the exergy mismatch between the energy demand and supply. The latent exergy load cannot be disregarded for building thermal load and energy flows analysis, especially for buildings in humid climate. Large exergy loss, which is dominated by solar gain, was found in all five reference buildings across different climate zones. This study provides a comprehensive understanding of building thermal load and related energy flows, and would benefit building evaluation and thermal design of building envelop.

Analysis of Energy Flow Path Model Based on Spatial Layout Features of Buildings

Energy flows in buildings through a variety of paths that influence each other to form a dynamic balanced and self-adjusting system. By controlling and changing the energy exchange between the building system and the environment and building energy flow directions, and organizing the various energy flow paths, the building system achieves systematically thermal stability

Big-data for building energy performance: Lessons from assembling a very large national database of building energy use

Building energy data has been used for decades to understand energy flows in buildings and plan for future energy demand. Recent market, technology and policy drivers have resulted in widespread data collection by stakeholders across the buildings industry. Consolidation of independently collected and maintained datasets presents a cost-effective opportunity to build a database of unprecedented size. Applications of the data include peer group analysis to evaluate building performance, and data-driven algorithms that use empirical data to estimate energy savings associated with building retrofits. This paper discusses technical considerations in compiling such a database using the DOE Buildings Performance Database (BPD) as a case study. We gathered data on over 750,000 residential and commercial buildings. We describe the process and challenges of mapping and cleansing data from disparate sources. We analyze the distributions of buildings in the BPD relative to the Commercial Building Energy Consumption Survey (CBECS) and Residential Energy Consumption Survey (RECS), evaluating peer groups of buildings that are well or poorly represented, and discussing how differences in the distributions of the three datasets impact use-cases of the data. Finally, we discuss the usefulness and limitations of the current dataset and the outlook for increasing its size and applications.

Simplified evaluation method for energy efficiency in single-family houses using key quality parameters

In practice a number of calculation tools are used to calculate annual energy flows in buildings. Their use yields accurate results but requires the input of a large number of parameters in the complex calculation procedures involved. The values of these parameters are usually known only after the planning process of a building has been completed.A simplified evaluation method for energy efficiency in single-family houses has been developed with the aim of using as few building parameters as possible with the simplest calculation procedures possible. The calculation model was created on the basis of results obtained in a research study conducted on a large statistical sample of Slovenian single-family houses. The correlation analysis carried out showed that the heat balance energy flow values calculated are closely related to certain building quality parameters. The energy balance complexity makes normal quantity parameters less related to energy flows, and they cannot be used in simplified evaluation models.The new evaluation method can be used in two modes by applying different quality parameters, depending on their availability. If more complex input parameters are used, the results of the method are more accurate, and so it can also be used for a preliminary assessment of individual projects.

Influence of display cabinet cooling on performance of supermarket buildings

Energy demand attributable to the operation of supermarkets is thought to be responsible for 1% of UK greenhouse gas emissions. Current building regulations in the UK require the “building related” energy use of new commercial buildings to comply with particular requirements. Supermarket buildings are therefore modelled in considerable detail, according to these protocols to establish their predicted energy demand. Lighting, occupancy, and small electrical energy impacts are included in this modelling. However, a large gap is found between the design outputs of this modelling and the energy performance of the store in operation. One reason for this is that thermal interactions at the refrigeration cabinets are not included in this modelling, as refrigeration is classified as “process energy” rather than “building related.” This paper explores the comparative energy demands of supermarket retail floors simulated both with and without the cooling effect of refrigeration cabinets included in the simulation. The retail floor of a recently built supermarket is modelled using EnergyPlus. Practical applications: It has been shown that the energy demand of the retail floor of a new store could be reduced by 25% by improvement of the envelope, by halving ventilation rates and doubling insulation levels. This has been shown by simulation of the building energy flows with refrigeration cabinets included in the modelling (whereas these are currently excluded as process energy). Changes in modelling protocols, and regulations, to encompass refrigeration energy transfers, could reduce the national load, due to supermarkets, by at least 140 MW in 5 years. Energy costs to the retailer would be reduced by 20%. Additionally, the simulation has shown the contribution of rooflights to the reduction of energy demand to be lower than previously predicted, saving only around 1/3 of design expectations.

Optimizing the configuration of a façade module for office buildings by means of integrated thermal and lighting simulations in a total energy perspective

The building enclosure plays a relevant role in the management of the energy flows in buildings and in the exploitation of solar energy at a building scale. An optimized configuration of the façade can contribute to reduce the total energy demand of the building.Traditionally, the search for the optimal façade configuration is obtained by analyzing the heating demand and/or the cooling demand only, while the implication of the façade configuration on artificial lighting energy demand is often not addressed.A comprehensive approach (i.e. including heating, cooling and artificial lighting energy demand) is instead necessary to reduce the total energy need of the building and the optimization of the façade configuration becomes no longer straightforward, because non-linear relationships are often disclosed.The paper presents a methodology and the results of the search for the optimal transparent percentage in a façade module for low energy office buildings. The investigation is carried out in a temperate oceanic climate, on the four main orientations, on three versions of the office building and with different HVAC system’s efficiency. The results show that, regardless of the orientations and of the façade area of the building, the optimal configuration is achieved when the transparent percentage is between 35% and 45% of the total façade module area. The highest difference between the optimal configuration and the worst one occurs in the north-exposed façade, while the south-exposed façade is the one that shows the smallest difference between the optimal and the worst configuration.

Analysis of Computational’s Software Resources for Simulation and Modeling of Energy Flows in Buildings

Analysis of Computational’s Software Resources for Simulation and Modeling of Energy Flows in Buildings

Integration of plug-in hybrid electric vehicles into energy and comfort management for smart building

The smart building and plug-in hybrid electric vehicle (PHEV) are two promising technologies. The integration of these two emerging technologies holds great promises in improving the power supply reliability and the flexibility of building energy and comfort management. The overall control goal of the smart building is to maximize the customer comfort with minimum power consumption. In this study, multi-agent technology coupled with particle swarm optimization (PSO) is proposed to address the control challenge. The proper aggregation of a number of PHEVs turns out to be able to provide both capacity and energy to make the building more economical and more reliable by impacting the building energy flow. Case studies and simulation results are presented and discussed in the paper.

A qualitative energy-based unified representation for buildings

This paper presents the development of energy-based unified representations for buildings called Archi Bond Graphs and then specialises them as qualitative Archi Bond Graphs that combine graphical representations and qualitative equations. They can be applied to simulations of people behaviour and people-energy behaviour in space-people systems, building energy flows and building energy variations in different building energy systems, and energy interactions between these building subsystems. The applicability of qualitative Archi Bond Graphs is demonstrated through a building simulation for the dynamic energy interactions between the space-people system and building energy systems, including lighting system, and hydraulic system in a town-house design.

Building Zonal Thermal and Airflow Modelling - A Review

The amount of energy used to heat and cool buildings is a significant concern that impacts on issues from national policies to personal desires of cost and comfort. The key to achieving optimum performance is the control of the energy flows in the building and its environment. Such control is secured through monitoring and altering the driving sources to maintain the desired thermal and air quality conditions in a space while external and internal conditions (e.g. seasonal climate, indoor heat gains, pollutants etc.) change over time. Thermal modelling tools are essential for the energy efficient design of buildings and their associated control systems. They are used for a wide range of tasks including policy making, cost analysis and comfort evaluation.This paper reviews the evolution of zonal airflow and thermal models, principally for single room analysis, used to design and control heating and cooling in the built environment. Insight is offered into the problems of modelling building energy flows and the results of various models are compared with experimental measurement. Finally, current state-of-the-art modelling is reviewed with emphasis on the development of models that designers and engineers can use to obtain a more accurate evaluation of building energy flows.

Improved direct solver for building energy simulation

Finite-difference methods, when applied to the differential equations modelling energy flows in buildings, give rise to a system of non-linear difference equations. A frequently used direct solution method involving linearisation is analysed and a related method is proposed. These and one other connected method are compared using a building-related test problem prepared for this purpose. The proposed numerical method is found to produce least error, about 30% less than the commonly used method, and it is recommended for inclusion in building energy simulation software. A fundamental method for estimating the pre-conditioning period of a building, arising from the work, is discussed.

Energy program validation: conclusions of IEA Annex I

Computer programs for predicting the energy consumption of a building are providing architects and building services engineers with very valuable aids to assist them in the design function. The calculation of building energy flows is extremely complex, and so validation is a vital element in the development of any model. Under the auspices of the International Energy Agency, 23 computer program owners from 8 different countries collaborated in a joint R&D project to compare energy programs, both in terms of consistency between programs, and in considering the accuracy of these same programs in modelling the behaviour of a real building. This paper summarizes the major conclusions that developed out of the project, and gives insight into some of the most important aspects which need to be considered in the development of a reliable computer program.